The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The present disclosure is related in general to fluid compositions and methods for servicing subterranean wells. Particularly, embodiments relate to the use of fluids containing fibers. Such fluids are also referred to as “fiber-laden fluids.”
The inclusion of fibers in fluids for servicing subterranean wells has become a well-known practice. For example, fibers are added to drilling fluids to help minimize lost circulation. Similarly, fibers may be added to cement slurries to help minimize lost circulation; fibers can also improve flexural strength of set cement. In hydraulic fracturing operations, fibers may be added to proppant to help prevent proppant flowback as the well produces. Fibers are also used to improve the solids-carrying capacity of fluids as they are pumped downhole for various purposes.
A thorough presentation of the use of fibers in well-service fluids may be found in the following publications.    Armstrong K. et al.: “Advanced Fracturing Fluids Improve Well Economics,” Oilfield Review 7, no. 3 (Autumn 1995): 34-51.    Abbas R. et al.: “A Safety Net for Controlling Lost Circulation,” Oilfield Review 15, no. 4 (Winter 2003/2004): 20-27.    Bivins C. et al.: “New Fibers for Hydraulic Fracturing,” Oilfield Review 17, no. 2 (Summer 2005): 34-43.    Daccord G. et al.: “Cement-Formation Interactions,” in Nelson E. B. and Guillot D. (eds.): Well Cementing—2nd Edition, Houston: Schlumberger (2006): 191-232.
Many fibers are supplied by manufacturers in the form of packets or “tows.” Tows are fiber bundles that are held together by a resin, a surfactant or a crimp. The fibers are aligned, not twisted. Chemical binding agents for this purpose are known in the industry as “sizing,” and their compositions are generally proprietary. Tows improve the surface handling of the fibers, preventing premature dispersion. However, upon addition to a liquid, the tows are designed to break apart very quickly into individual fiber strands. An example of fiber packets may be found in WO 00/49211.
During normal wellsite operations, a fiber suspension is prepared by adding the fibers to a fluid in a tank. The mixture is agitated to disperse the fibers and then pumped through a pipe. However, when a large fiber concentration is required, the preparation and pumping of the suspension may become difficult if not impossible due to the inherent property of fibers to form clumps or flocs. The flocs may accumulate on the paddle of the mixer, plug orifices, obstruct pump valves, etc. This imposes a limit on the fiber concentration that can be used during wellsite operations. As a result, the maximum allowable fiber concentration may not be sufficient to attain the optimal fluid properties for the intended application.
Despite many advances made by the well-service industry concerning the delivery and dispersion of fibers, it still would be valuable to provide means to increase the concentration of fibers in wellbore-service fluids, and avoid the negative consequences described above.